High power variable inductor



May 13; 1969 4. T. LIERLEY ET AL H IGH POWER VARIABLE INDUCTOR Sheet Filed Nov. 17, 1967 y 1969 J. 4T. LIERLEY ET AL 3,444,494

- mu POWER VARIABLE mnucwon Filed Nov. 17, 1967 Sheet 3 of 2 United States Patent 3,444,494 HIGH POWER VARIABLE INDUCTOR John T. Lierley, La Habra, and Kenneth E. Clissett, Newport Beach, Calif., assignors to Hughes Aircraft Company, Culver City, Calif., a corporation of Delaware Filed Nov. 17, 1967, Ser. No. 683,879 Int. Cl. H01f 27/10, 29/06; H01c 5/00 US. Cl. 33662 4 Claims ABSTRACT OF THE DISCLOSURE The device of the present invention provides a stepless variable inductor with firm contact at any specified inductance within the range of the coil without using slidingor rolling contacts. Stepless contact is achieved by means of a rotary hydraulic interface which enables the use of a bellows-operated clamp contactor featuring pressure actuation and liquid cooling. An inherent advantage of this device is the firm grip contact with the coil and center tube effected by a non-magnetic clamping mechanism which disposes of problems of burning at the point of contact and over heating of the actuation device by the high power electromagnetic field.

Background of the invention The device of the present invention constitutes a high power variable inductor. Contemporary devices of this type involve the use of rollers which are concave at their outside diameters so as to approach the cross section of the coil material, giving at best a line of contact under light pressure. This has been found to be unsatisfactory for high power service which requires a positive contact. Another contemporary device converts a variable portion of a coil into a coaxial line by shielding varying portions of the coil with a helical baflie screwed into the convolutions thereof. Also in use are tapped coils for step tuning.

Summary of the invention In accordance with the present invention, a liquid cooled helical coil is mounted about a keyed rotatable shaft on which is slidably mounted a bellows-operated clamp contactor. The bellows-operated clamp contactor has adjustable cone contacts at the coil and at the center shaft and may be driven by rotation of the keyed rotatable shaft through numerous revolutions without the rolling or sliding of an electrical contact to any point along the helical coil where a desired inductance is indicated. Cooling and operating fluids for the bellows-operated clamp contactor are provided through a multichanneled rotary hydraulic interface having an anti-rotating linkage securing its housing and a keyed hole to transmit torque from the keyed shaft to a center rotatable portion thereof wherefrom conduits for the operating and cooling fluids emanate. The rotary hydraulic interface is adapted to slide along the keyed shaft along with the bellows-operated clamp contactor.

The bellows-operated clamp contactor of the device of the present invention achieves a firm grip on the helical coil and keyed rotatable shaft thereby disposing of the problem of burning at the point of contact inherent in contemporary devices. In addition, the rotary hydraulic interface enables the use of pressure actuation and liquid cooling thereby obviating the need for a magnetic actuation device Within the coil environment. A magnetic actuation device would normally be destroyed by any high-power electromagnetic field generated by current flow in the helical coil.

Brief description of the drawings FIG. 1 shows a side view of the apparatus of the present invention in cross section; and

FIG. 2 is an end view of the apparatus of FIG. 1 from the right extremity as seen in the drawing.

Description Referring to FIG. 1 of the drawings, there is shown a sectional view of the apparatus of the invention. In particular, a hollow rigid helical conductor 10, which constitutes the maximum inductance available from the apparatus, is supported by supports 11, 12, shown only in part. An inlet 13 and an outlet 14 at opposite extremities of helical conductor 10 provide means for passing a coolant therethrough.

A non-rotatable conductive clamp support tube 15 is disposed through the center of helical conductor 10. The clamp support tube 15 is sealed off -by a disc 16 near the right extremity of helical conductor 10 leaving an extension 17 for support purposes. The main portion of tube 15 is cooled by the insertion of a tube 18 into the tube 15 almost to the disc 16, providing a seal 19 between tubes 15 and 18 and attaching an outlet 20 to tube 15 and an inlet 21 to tube 18. Thus, the clamp support tube 15 may be cooled by circulating a coolant through inlet 21 and tube 18 to disc 16 and back along the outside of tube 18 through tube 15 to the outlet 20. A rotatably mounted dielectric shaft 22 of square cross section with a cylindrical extension 23 fitted with bronze bearings 24, 25 is inserted into the extension 17 of tube 15 in a manner to provide support for the adjacent extremities of tube 15 and shaft 22.

Referring to FIGS. 1 and 2, a hydraulic interface device 26 includes a circular non-rotating housing 27 disposed about a rotatable core 28 which provides a circular flange 48 beyond the left side of housing 27, as viewed in the drawing, and also is slidably mounted and keyed to the square shaft 22. A retaining plate 29 fastened to the rotatable core 28 retains the housing 27 in place. The rotatable core 28 includes circumferential fluid channels 30, 31, 32 which are sealed and isolated by the use of 0- rings between the rotatable core 28 and housing 27. External connection to the fluid channels 30, 31, 32 is made through flexible non-conductive tubes 33, 34, 35 and fittings 36, 37, 38, respectively, which, in turn, are connected to holes which terminate over respective circumferential fluid channels 30, 31, 32. Thus, regardless of the angular position of housing 27 with respect to the rotatable core 28, the flexible tubes 33, 34, 35 are connected to the fluid channels 30, 31, 32, respectively. The housing 27 is prevented from rotating by means of a linkage assembly 40 which has one extremity rotatably connected to one side thereof and has a transverse pin 41 on a remaining extremity that restricts its motion to a slot 42 disposed normal to the square shaft 22 in a bracket 43. The interface is completed by holes through the rotatable core 28 from the fluid channels 30, 31, 32 to ports 45, 46, 47 (FIG. 2) spaced in the flange portion 48 at the left extremity of core 28 as viewed in the drawing.

A tubular carriage 50 having a flange portion 51 attached to the flange portion 48 of rotatable core 28 of interface 26 extends to and rotates about the support tube 15 by means of a carriage bearing ring 52 and supports a clamp body 55 of a bellows-operated clamp connector 54 by means of a flange 53 at the left extremity of cartriage 50, as viewed in the drawing. The clamp body 55 of the bellows-operated clamp contactor 54 is fabricated of conductive material in a basic U configuration that is closed across the extremities of the straight portions with the curve portion disposed over a segment of the helical conductor and the straight portions thereof being sufliciently wide (FIG. 2) to accommodate an aperture for the support tube 15. An inlet 56 and an outlet 57 are provided for coolant tubes (not shown) which extend through the clamp body 55 to enable a coolant to be circulated therethrough. Dielectric helix followers 58, 59 are disposed through the clamp body 55 on opposite sides of the helical conductor 10 for the purpose of guiding the bellows-operated clamp contactor 54 therealong when rotated. Electrical contact from the clamp body 55 to the helical conductor 10 is provided by an adjustable contactor 60 disposed through the center of the curved portion of the U-shaped body 55. In addition electrical contact is provided between the clamp body 55 and the support tube by means of an adjustable contactor 61 disposed through the center of the closed end of the U- shaped body 55. Adjustable electrical contacts 60, 61 are set, in the absence of pressure, to be close to the helical conductor 10 and support tube 15, respectively, and yet allow the clamp body 55 to rotate.

A two-sided bellows base 62 is disposed between the straight portions of the U-shaped body 55 midway between the helical conductor 10 and the support tube 15. A tube 63 connects to holes 64, 65 which extend to the respective centers of opposite sides of the base 62. Bellows 66, 67 are mounted on opposite sides of the two-sided bellows base 62 and dielectric pads 68, 69 seated between the bellows 66 and helical conductor 10 and between the bellows 67 and the support tube 15, respectively. In the quiescent state the bellows 66, 67 do not apply pressure between the helical conductor 10 and the support tube 15. Bleed connections 70, 71 are provided at the extremities of bellows 66, 67 furthest from the base 62, respectively. Lastly, a conduit 72 connects the port 46 to the tube 63 from the bellows base 62 and conduits 73, 74 connect the inlet 56 and outlet 57, respectively, to ports 45, 47 in the flange 48 of the rotatable core 28. Thus, flexible tubes 33, 35 provide means of circulating a coolant through the body 55 and flexible tube 34 provides a fluid connection to the bellows 66 and 67 of the bellowsoperated clamp contactor 54.

In order to place the variable inductor of the present invention into operation, it is first desirable to bleed any air from the bellows 66, 67 by use of the bleed connections 70, 71 by rotating the clamp body 55 to a vertical orientation and releasing any air from the top bleed c nnection 70 or 71. With no hydraulic pressure applied to the bellows 66, 67, the square shaft 22, which drives rotatable core 28 and carriage 50, is used to turn the bellows-operated clamp contactor 54 to a predetermined point along the helical conductor 10. The exact location of this point is determined by frequency selection and prior calibration. Upon reacting the desired point along the helical conductor 10, hydraulic pressure is applied through the flexible tube 34, hydraulic interface device 26, conduit 72, tube 63 and the bellows base 62 to the bellows 66, 67 which expand pressing the dielectric pads 68, 69 against the helical conductor 10 and the support tube 15, respectively, which are sutliciently flexible to allow firm contact with the adjustable contactors 60, 61. Thus, the helical conductor 10 is electrically connected to the conductive support tube 15 through the body 55 of the bellows-operated clamp contactor 54 whereby the output inductance of the device appears between inlet 13 and support tube 15. If it is desired to change this inductance, the pressure on flexible tube 34 is first released prior to rotating the square shaft 22 thereby to rotate the clamp contactor 54 to a new position.

We claim:

1. A variable inductor adapted for use in a high intensity electromagnetic field, said variable inductor comprising a hollow conductive helix for providing the maximum inductance realizable from said variable inductor; a straight cylindrical conductor disposed lengthwise through the center portion of said helix; a keyed shaft rotatably connected to said straight cylindrical conductor at one extremity thereof, said keyed shaft having a length no less than that of said helix; a hydraulic interface device having a rotatable core slidably mounted on and keyed to said keyed shaft; a rotatable connector disposed about corresponding segments of said straight cylindrical conductor and said conductive helix, said rotatable connector including a bellows intermediate said helix and said straight conductor; means of a length no less than that of said helix connecting said rotatable connector to said rotatable core of said hydraulic interface device whereby rotation of said keyed shaft rotates said rotatable connector about said straight cylindrical conductor along the convolutions of said helix; and means connected through said hydraulic interface device to said bellows for causing said bellows to expand between said straight cylindrical conductor and said helix thereby to cause said rotatable connector to make a firm electrical contact therebetween.

2. The variable inductor adapted for use in a high intensity electromagnetic field as defined in claim 1 which additionally includes means connected to opposite extremities of said hollow conductive helix for circulating a coolant therethrough; means connected to the extremity of said straight cylindrical conductor opposite from said one extremity thereof for circulating a coolant therethrough; and means for circulating a coolant serially through said hydraulic interface device and said rotatable connector.

3. The variable inductor adapted for use in a high intensity electromagnetic field as defined in claim 1 wherein said hydraulic interface device having a rotatable core comprises means for providing said rotatable core including a cylindrical body having a keyed hole therethrough adapted to accommodate said keyed shaft and no less than one circumferential channel therearound, a flange at one extremity thereof, and a hole through said cylindrical body and said flange from said circumferential channel to a port in said flange on the side thereof opposite said cylindrical body; a housing coextensive with and surrounding said cylindrical body; means attached to said housing for preventing said housing from rotating; means intermediate said housing and said cylindrical body for providing a hydraulic seal on both sides of said no less than one circumferential channel; means for providing a hydraulic connection through said housing above said no less than one channel; and a disc attached to the extremity of said cylindrical body opposite from said one extremity thereof for retaining said housing in fixed relation with respect to said cylindrical body.

4. A variable inductor for use in a high intensity electromagnetic field, said variable inductor comprising a hollow conductive helix of a length no less than the maximum inductance to be realizable from said variable inductor; a straight conductive tube disposed through the center of said helix; a square shaft having a cylindrical extension inserted in said straight cylindrical tube for providing a rotatable connection thereto, said square shaft having a length no less than that of said helix; a hydraulic interface device having a rotatable core slideably mounted on said square shaft; a rotatable connector disposed about corresponding segments of said straight cylindrical tube and said conductive helix, said rotatable connector including first and second bellows disposed intermediate said helix and said straight cylindrical tube for making positive electrical contact therewith; means of a length no less than that of said helix for mechanically connecting 5 6 said rotatable connector to said rotatable core of said References Cited 7 hydraulic interface device whereby rotation of said square UNITED STATES PATENTS shaft rotates said rotatable connector about said straight 1,845,406 2/1932 Gebhard 3 XR cylindrical tube along the convolutions of said helix; and 2139443 12/1938 Craymer 336 139 XR means for providing a hydraulic connection through said 5 3,078,430 2/1963 Majkrzak 336-140 hydraulic inter face device to said first and second bellows LEWIS H. MYERS Primary Examiner for causing said bellows to expand between sa1d straight cylindrical tube and said helix thereby to cause said ro- KOZMA Assistant Examinertatable connector to make a firm electrical contact there- 10 US. Cl. X.R.

between at a selected position along said helix. 338143 

